docs: def remove_unit_core(self):
          """
              If an unsatisfiable core contains only one clause :math:`c`, this
              method is invoked to add a bunch of new unit size hard clauses. As
              a result, the SAT oracle gets unit clauses :math:`(\\neg{l})` for
              all literals :math:`l` in clause :math:`c`.
          """
  
          self.scpy[self.core[0]] = False
  
          for l in self.soft[self.core[0]]:
              self.hard.append([-l])